PAX® is the first quantitative multiplex macroarray specifically designed for companion animals that tests for both allergen extracts and molecular components.
Molecular allergology is a state-of-the-art approach to the detection of sensitisations, whereby defined single allergen components are used for the determination of specific IgE in place of traditionally-used allergen extracts. The molecular components are recombinant proteins that provide a higher level of standardisation than allergen extracts and enable a more precise identification of IgE sensitisations.
Molecular allergology tests are powerful tools that help pinpoint allergy triggers, thus facilitating risk assessment and therapy decisions
Key Facts about PAX®:
- First quantitative multiplex macroarray specifically designed for companion animals
- Over 200 allergens included = lower testing cost per allergen (see list of allergens)
- Fully automated process = higher level of standardization (same result if tested multiple times)
- With CCD blocking and 2 blocking efficiency detectors
- Only 0.5 ml of serum needed per test
- Expected increase in serological test sensitivity due to a higher concentration of molecular allergens
- Identification of ”primary” sensitizing allergens
- Identification of allergen cross-reactivities
- Selection of relevant allergens for specific immunotherapy
- Guaranteed 100% reliable screening test
- Fast results
- Continuous support and advice with our vet allergy experts
Ask your vet about this product.
Why are food allergens included in the PAX?
Currently, the review of existing evidence suggests that the testing (intradermal, prick, patch or IgE serological) for food allergens does not accurately predict the clinical diagnosis of food allergy in animals except for a non-negligible negative predictive value of some IgE serological tests.
However, “food allergy” only represents an imprecise etiological diagnosis that manifests in a myriad of different clinical diagnoses. While some of these diagnoses are clearly IgE-mediated (e.g., urticaria, angioedema, anaphylaxis), others have a suspected cell-mediated pathogenesis (say, the eosinophilic or lympho-plasmacytic enteropathies). For food-induced atopic dermatitis, there is evidence of both IgE- and/or lymphocyte-mediated mechanisms. As a result of this variety of mechanisms, looking at the usefulness of any single test for the diagnosis of all food allergies is senseless. It would be like looking at the usefulness of urine bacterial culture for the diagnosis of all bacterial infections, when it would only be valid for urinary tract infections!
In the context above, the PAX only represents a test for the detection of IgE sensitizations to food allergens. These food allergies are those that would manifest as immediate reactions after the ingestion of food ingredients, that is reactions within minutes to hours after an oral food challenge. The diagnosis of food-induced urticaria, atopic dermatitis, etc… should only be made by the clinician after an oral food challenge.
As for humans with food allergies, we believe that such food challenges would be best oriented with the determination of food allergens to which the patient is IgE-sensitized.
Of importance is that our analysis of more than 1,000 sera from dogs suspected of allergic disease revealed only half of the dogs reacting to an average of only 2.7 food allergens. Notably, most positive reactions were concordant (e.g., dogs reacting to several fish tropomyosins, or egg extracts and associated components, or various soybean components, etc…) suggesting an excellent internal consistency of the PAX. Additional studies are ongoing to confirm the relevance of the PAX for the diagnosis of immediate IgE-mediated food allergy subsets in pets.
What sample type can I submit?
It is preferable to submit serum rather than plasma for the PAX®. A minimum of 0.5 ml is requested to allow for repeated testing in case of need.
Is there any interference from icterus, lipemia and hemolysis?
There is no relevant influence of icterus, lipemia or hemolysis on the PAX® results.
Are cross-reactive carbohydrate determinants (CCD) blocked?
Each animal serum tested is diluted in a buffer that contains a proprietary mix of proteins that contain different types of CCDs. The PAX® is also the first veterinary serological test that has incorporated CCD detectors on each cartridge to verify the efficiency of the CCD blocking. In case one of these detectors yields elevated levels of anti-CCD IgE after the initial blocking, the serum is retested a second time after incubation with a higher amount of a different CCD blocker. This second incubation results in a marked decrease in CCD-specific IgE and a noticeable reduction in the number of pollen and plant food IgE positivities.
What volume of serum do I need to send?
0,5 ml of serum per test.
How long does it take for the results to be ready?
Results are available 2 days after arriving at our laboratory.
Which anti-IgE reagent is used in the PAX®?
For the canine test, the PAX® uses the anti-dog IgE monoclonal 5.91, which was produced in the 1990’s by Prof. Bruce Hammerberg at the NC State University College of Veterinary Medicine. This antibody recognizes an epitope in the Ce2 segment of the Fc-fragment of canine IgE. The epitope is distinct from the IgE regions that bind to the high- and low-affinity IgE receptors, thus ensuring that there is no interference from the soluble IgE receptors that are naturally present in allergic dogs. Of importance is that the sequence of the epitope recognized on dog IgE is completely different from that present on canine IgM, IgA and the four different IgG subclasses (IgG1 to IgG4). In fact, we verified, using both standard ELISA and the PAX® that the 5.91 antibody does not bind to canine IgG.
How are the results reported?
The reports contain four distinct sections:
A graphic color-coded summary of the positivities, and,
A text summary of the positivities, and,
An expanded interpretation of the nature of the positive extracts and components.
What is the precision of the assay?
The precision was determined in two different conditions:
For the cartridge lot-to-lot variation, two different lots were compared using 54 allergen/sample combinations covering 44 allergens. For the specific IgE values lower than 400 ng/mL, the intra-assay coefficient of variation was 3.0% and the inter-assay coefficient was 7.1%. For the values above 400 ng/mL, these CV% were 2.0 and 5.2%, respectively.
For the determination of the repeatability, three canine serum samples were tested in duplicates in five different runs. As above, for the lower IgE values, the intra- and inter-assay CV% were 6.2 and 8.2%, respectively; those for the higher values were 2.7 and 7.0%, respectively.
Bottom-line: The precision of the PAX® is excellent with results being highly reproducible.